Re: Three Kinds of Logical Trees

From: dawn <dawnwolthuis_at_gmail.com>
Date: 28 Jul 2005 08:00:38 -0700
Message-ID: <1122562838.385980.183040_at_g47g2000cwa.googlegroups.com>


Jonathan Leffler wrote:
> dawn wrote:
> > Gene Wirchenko wrote:
> >> What are the two values of your logic? I use true
> >
> > for the physical switch being set to the up position, right?
> >
> >>and false
> >
> > and down position. Yes, Gene, those are the two I choose as well,
> > ignoring the shades of gray. --dawn
>
> These comments suggest an American (USA) perspective on the polarity of
> switches. In the UK, a (light) switch that is up is normally off and
> one that's down is normally on - at least, for most switches. It still
> catches me out.

I have never thought about whether hardware switches had this same pattern. I wasn't referring to just any switches, but those found on the front panel of a computer way back when. I hit the tail-end of the hardware switch era, but I do recall setting physical switches in the late 70's. This was then imitated with parameter settings. Well into the 80's I recall variables named with -sw or -switch if they held values of 1 or 0.

So, I wonder if computers in the UK had hardware switches reversed from US hardware. Were there computers where up was 0 and down was 1? --dawn

> (I hope I have the attributions right - apologies if not.)
>
> --
> Jonathan Leffler #include <disclaimer.h>
> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
> Guardian of DBD::Informix v2005.01 -- http://dbi.perl.org/
Received on Thu Jul 28 2005 - 17:00:38 CEST

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